U.S. Pat. No. 7,793,601 to Davison et al. entitled “Side Feed/Centre Ash Dump System” describes a gasifier for gasifying solid fuel, including solid organic materials. The gasifer includes a primary oxidation chamber having an inner surface lined with a refractory material. An inlet opening in one of the sides is provided for infeed of the solid fuel into the primary oxidation chamber. A storage container stores the solid fuel, and a transfer means connects the storage container with the inlet opening for transferring in an upwardly inclined direction the solid fuel from the storage container through the inlet opening into the primary oxidation chamber to form an upwardly mounted fuel bed of the solid fuel including the organic materials on the bottom of the primary oxidation chamber. The transfer means includes a hydraulic ram feeder and a compression tube, the hydraulic ram feeder driving fuel from the storage container into the compression tube, thereby compacting the fuel. Means are provided for supplying an oxidant into the primary oxidation chamber to gasify the solid organic materials to produce a gaseous effluent, thereby leaving a residue of solid fuel. Means are provided for removing the gaseous effluent from the primary oxidation chamber. An opening in the bottom of the primary oxidation chamber has mounted thereunder a means for the removal of the residue, including a walking-floor feeder.
U.S. Pat. No. 7,322,301 to Childs describes a method for processing wet sewage sludge or other feedstock including carbonaceous material principally composed of wet organic materials in a gasifier to produce useful products. The sludge or feedstock is first dewatered using thermal energy in a location separate from the gasifier. The feedstock is processed with a small amount of oxygen or air present at a temperature required to break down the feedstock and generate producer gas and char in the gasifier. Some of the fuel produced during the feedstock processing step is fed back to the separate location and burned to provide the thermal energy required in the feedstock dewatering step and thereby minimize or eliminate the need for external energy to dry the wet feedstock.
U.S. Pat. No. 6,120,567 to Cordell et al. describes a method for gasifying solid organic materials to produce a gaseous effluent and solid residue. A primary oxidation chamber having a converging upper portion and a bottom portion are provided. Solid organic materials are introduced into the primary oxidation chamber upwardly from the bottom portion of the primary oxidation chamber to provide a mass of solid organic materials in the primary oxidation chamber. The mass of solid organic materials is heated in the primary oxidation chamber. An oxidant is added to the primary oxidation chamber to gasify the heated mass of solid organic materials in the primary oxidation chamber and to initiate a flow of gaseous effluent within the primary oxidation chamber. A gaseous effluent flow path is established within the primary oxidation chamber, whereby a portion of the gaseous effluent repeatedly flows in a recirculating upward and downward direction through the heated solid organic materials to enhance continuous oxidation of the solid organic materials. A further portion of the gaseous effluent flow is advanced in a direction outward from the primary oxidation chamber. The solid residue is then transferred out of the primary oxidation chamber.